By Dr. Allison Smith, ZRT Laboratory Sex Hormone Binding Globulin (SHBG) is one of the most overlooked variables in hormone health. It directly controls how much testosterone is biologically active in your body — yet it rarely appears on standard blood panels. Whether you're dealing with symptoms of low testosterone, androgen excess, or unexplained hormonal imbalance, understanding SHBG is essential to getting the full picture. What is SHBG? SHBG is a protein produced primarily in the liver that binds tightly to testosterone — and to a lesser degree, oestradiol (E2) and dihydrotestosterone (DHT) — and carries them through the bloodstream....
When it comes to topical testosterone therapy, more is not always better. Dr. Allison Smith of ZRT Laboratory explains the U-shaped curve phenomenon — where both too little and too much testosterone produce the same symptoms — and why starting at low doses and titrating carefully is essential. She also outlines the key markers to check when a man’s testosterone numbers look good on paper but his symptoms persist.
Testosterone has long been associated with aggression — but new research is revealing a far more nuanced picture. A study published in Nature Communications, involving ZRT Laboratory, found that a single dose of testosterone significantly increased young men’s preference for luxury, status-enhancing goods. Dr. Kate Placzek explores the neuroendocrine science behind this finding — and what it reveals about testosterone’s role in dopamine, reward and social behaviour.
The Women’s Health Initiative (WHI) trial cast a long shadow over hormone replacement therapy — but it enrolled women well over a decade past menopause. Two newer trials, ELITE and KEEPS, specifically studied HRT started early in the postmenopausal period. Their findings on cardiovascular health, sexual function, sleep, mood and cognition paint a more nuanced and encouraging picture. Here is what the latest research shows.
An FDA-approved testosterone gel was shown to significantly increase cardiovascular risk in older men — but does this mean testosterone therapy is dangerous? ZRT Laboratory’s research suggests the real problem lies in how testosterone is measured. Venous serum testing dramatically underestimates tissue exposure to topical testosterone, leading to pharmacological overdosing that goes undetected. This article explains why the testing method matters as much as the dose.
